(a) Field of the Invention
The present invention relates to a method and an apparatus for signal detection, and more particularly, to a method and an apparatus for signal detection in a multi-input multi-output wireless communication system.
(b) Description of the Related Art
In a wireless communication system, since a bandwidth is very limitative, it is very important to support high data transmission rate to various users by using only the limitative bandwidth. A multi-input multi-output (hereinafter referred to as “MIMO”) communication system has several antennas on a transmission terminal and a reception terminal, and simultaneously transmits multiple signals by using the same wireless band on the transmission terminal in order to meet the above-mentioned requirement. As a result, it is possible to remarkably improve the transmission rate without increasing the bandwidth.
In the MIMO communication system, the transmitter transmits different data by using a plurality of antennas, and in this case, a signal of each antenna experiences independent fading. Therefore, the receiver should differentiate transmitted data through proper signal processing. At this time, signals transmitted from another antenna are overlapped and thus cause inter-antenna interference (IAI), which is an interference factor that increases errors.
As a method of detecting the transmitted data while removing the interference factors, a maximum likelihood (hereinafter referred to as “ML”) detection method is used. This method shows the best performance, but is very high in complexity of a signal detecting process. In particular, as the number of transmission antennas increases, the complexity increases exponentially.
As a result, in case of actual system implementation, a signal detection method that does not have high complexity is used. As the signal detection method, a minimum mean square error-successive interference cancellation (hereinafter referred to as “MMSE-SIC”) scheme is used. In the MMSE-SIC scheme, when one symbol is first detected in transmission data, that is, a symbol is detected by the MMSE scheme, the symbol is excluded from the reception signal and the MMSE scheme is applied to the remaining symbols. The scheme is still lower in complexity but is worse in performance than the ML scheme.
An improved MMSE-SIC scheme has been recently proposed in order to solve the problem of deterioration in performance. The improved MMSE-SIC scheme should determine which symbol of the remaining symbols will be detected next whenever the symbol is detected. For this purpose, since a predetermined matrix determining the detection order should be calculated, the complexity is still low. Further, the improved MMSE-SIC scheme still has a large difference from the ML scheme in performance.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.